A LIGHTING SYSTEM AND A LIGHT COLLIMATION MODULE
A lighting system comprising: a duct providing a light transport passage for transporting light along a propagation direction parallel to a longitudinal axis of the duct, the duct comprising one or more light output surfaces through which light may be emitted, a light collimator having an input end and an output end, a light source arranged to direct light into the input end of the light collimator, a heat sink thermally coupled to the light source, and driver circuit for powering the light source, wherein at least one of the light collimator, light source, heat sink and driver circuit is arranged away from the longitudinal axis of the duct.
The invention relates to lighting systems, and more particularly to ducted lighting systems.
BACKGROUNDThe long-distance transport of visible light can be facilitated by mirror-lined light ducts and is employed in architectural lighting to deliver light throughout the interior parts of buildings. Mirror-lined ducts also provide advantages of large cross-sectional area and large numerical aperture (enabling larger fluxes with less concentration), a robust and clear propagation medium (that is, air) that leads to both lower attenuation and longer lifetimes, and a potentially lower weight per unit of light flux transported. Mirror-lined light ducts can be uniquely enabled by the use of 3M optical films, including mirror films such as enhanced specular reflector (ESR) films that have greater than 98% specular reflectivity across the visible spectrum of light.
Concurrently, LEDs are increasingly deployed as an energy saving replacement for traditional tungsten or fluorescent lighting systems. Lamps installed with LEDs typically have LEDs mounted on a plate, which is in turn affixed on a wall or ceiling, and the LEDs are arranged directly behind the light output surface of the lamp. LED lighting systems that use LED strips for a large room may consequently require installation of a plurality of LED strips throughout the room, along with sizeable driver circuit units for powering the LEDs. Heat generated by individual LED units on the strip requires effective dissipation to avoid overheating which could affect the lifespan of the LED units, but limited space exists in lighting systems, such as mirror-lined light ducts, to implement effective heat dissipation devices.
Given the myriad of competing factors such as those described above influencing the design of lighting systems and the ever increasing stringency end users place on both cost and performance, the need continues to exist for innovative approaches in developing new solutions.
SUMMARY OF INVENTIONIn one aspect, a lighting system is disclosed comprising a duct providing a light transport passage for transporting light along a propagation direction through the duct, the duct comprising a longitudinal axis and one or more light output surfaces through which light may be emitted, a light collimator having an input end and an output end, a light source arranged to direct light into the input end of the light collimator, a heat sink thermally coupled to the light source, and driver circuit for powering the light source, wherein at least one of the light collimator, light source, heat sink and driver circuit is arranged away from the longitudinal axis of the duct.
In another aspect, a light collimation module is disclosed, comprising a light collimator coupled to a duct, the light collimation module usable in a lighting system comprising: a duct providing a light transport passage for transporting light along a propagation direction through the duct, the duct comprising a longitudinal axis and one or more light output surfaces through which light may be emitted, a light collimator having an input end and an output end, a light source arranged to direct light into the input end of the light collimator, a heat sink thermally coupled to the light source, and driver circuit for powering the light source, wherein at least one of the light collimator, light source, heat sink and driver circuit is arranged away from the longitudinal axis of the duct.
These and other aspects of the invention are described in the detailed description below. In no event should the above summary be construed as a limitation on the claimed subject matter which is defined solely by the claims as set forth herein.
Throughout the specification, reference is made to the appended drawings, where like reference numerals designate like elements, wherein:
The figures are not necessarily drawn to scale. However, it will be understood that the use of a numeral to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number.
DETAILED DESCRIPTIONThe present disclosure describes a lighting system employing mirror-lined ducts designed to be compact and hence suitable for use in relatively cramped spaces, such as end-sections of a corridor. This is achieved by locating terminal components of the lighting system, such as the light collimator, light source, heat sink and driver circuit, away from the longitudinal axis of the duct. In other words, rather than arranging the these terminal components in a single file, i.e. in a straight line along the duct's longitudinal axis, which results in a lengthy terminal section, it is advantageous to arrange such components away from the duct's longitudinal axis, such as arranging the components at an angle of 90° or 180° to the longitudinal axis of the duct. In certain embodiments, such an arrangement results in the light source being emitted at 90° or 180° to the intended light propagation direction, so suitable joints or bends may be used to efficiently direct light from the light source into the duct, or from one duct section to another.
Referring to
The arrangement of the terminal component of the lighting system away from duct's longitudinal axis may be achieved in several ways.
In
The duct 140 defines a light transport passage 141. The duct 140 may be made up of 1, 2, 3, 4, 5 or more duct sections. Each duct section may be attached onto the ceiling or wall via nails or adhesive, or via fastening clips, and are coupled to each other via fastening clips or alternatively, each duct section may comprise mating end portions so that one duct section can be telescopically fitted to another duct section. Any other means of coupling duct sections together can also be used, where preferably the adjoining surfaces are well-fitting and do not suffer from light leaks.
Duct 140 may comprise individual duct sections 142, 144. The internal surface of each duct section 142, 144 is lined with a reflective material 160 to help reflect light within the duct 140. Examples of usable reflective materials include polished metal surfaces or specialty materials such as 3M Enhanced Specular Reflective (ESR) films. Other embodiments include mirror-lined ducts, such as reflective aluminum ducts, reflective acrylic ducts and optical grade polycarbonate ducts, or any other material capable of providing at least 90% reflectance, or more generally, at least 80% reflectance, or at the minimum 70% reflectance. Of the light rays that exit the light collimator 112, a substantial amount comprises collimated light rays 170. Non-collimated light rays 172 may be derived from light rays that are reflected off the internal surfaces of duct 140, or light rays 174 that are reflected off the surface of the light collimator 112. Light is hence propagated longitudinally through the duct, or in other words, light is transported along a propagation direction, as represented by arrow 179, that is parallel to the longitudinal axis of the duct.
Light exits the duct 140 via light output surfaces 150 located on the duct's surface. In one embodiment, each light output surface is arranged in a plane parallel to the longitudinal axis of the duct. Light therefore exits the duct in a direction, as represented by arrow 188, that is transverse to its propagation direction 179. Optical right angle films, such as 3M Transmissive Right Angle Films II (TRAF) may be used for this purpose. Advantageously, a single LED light source may be used to illuminate a duct ranging from several meters long to several tens of meters long, or preferably about ten duct sections of 1.2 meters each, i.e. total of 12 meters. Light rays 176 arriving at the end of the duct 140 are reflected off surface 165 and are recycled.
In general, joints may adopt any suitable configuration needed to connect components of the lighting system together and to alter the propagation direction of light in the lighting system from one component to the next. Techniques and apparatus used to extract and distribute light in ducts using joints and other light distribution components have been described, for example, in U.S. Pat. No. 8,251,527 entitled LIGHT DUCT BEND; Patent Publication Nos. US2012/0057350 entitled SWITCHABLE LIGHT DUCT EXTRACTION; WO2012/138503 entitled LIGHT DUCT TEE EXTRACTOR; WO2012/138595 entitled LIGHT DUCT TEE SPLITTER; WO2014/070498 entitled RECTANGULAR LIGHT DUCT EXTRACTION; and WO2014/168823 entitled ILLUMINATED LIGHT DUCT JOINT. In some embodiments, joints may be L-shaped or U-shaped for connecting two components together; joints may be T-shaped or E-shaped for connecting three components together, and so on, depending on the layout of the duct and light engine. Within the joints, light reflectors may be positioned to reflect light from the light source into the duct. In the context of this description, the term “joint” has the same meaning as the term “bend” and is used interchangeably throughout the description. Joints for connecting a light collimator to a duct is herein termed a “light collimator joint” or “light collimator bend”, and joints for connecting sections of the duct together are termed “duct joints” or “duct bends”.
Displacement of the light engine components away from the longitudinal axis of the duct may also be employed to reduce the vertical height of the lighting system in embodiments in which the light engine is vertically mounted.
In some embodiments, the light collimator 112 is configured in the shape of a conical or a pyramidal frustum, sometimes referred to as a reflective cone or pyramid. In other words, it is configured as a cone or pyramid structure in which the pointed end is removed, thereby having an opening 181 that serves as the input end of the light collimator and is attached to the heat sink. The large opening 182 serves as the output end for collimated light to exit.
In order to increase the surface area for heat dissipation, the light engine housing may comprise in an exemplary embodiment a metal casing that is thermally coupled to the heat sink 116, to enable the entire light engine housing to function as a heat sink of sorts. In some embodiments, the light engine housing may be configured as a secondary heat sink, to aid in the cooling of heat sink 116. Optionally, the heat sink 116 may comprise grooves 126 as shown in
In order to provide the light engine 110 with an appearance that is similar to the duct—a desirable goal from an aesthetic perspective—at least one of the length, depth or width of the light engine housing 120, as represented by arrows 191, 193, 195 in
LED array 115 may be a 3×3, 4×4, 5×5, or 6×6 LED array or any other size or configuration, delivering in various instances, a total of 5000, 10000, or 15000 or more lumens of light per LED array. As shown in
The following design rules for the light engine yielded favorable performance in the operation of the lighting system:
Size of the LED array=A×B
Area of output end of light collimator=(3A×3B)
Collimator length=12×B
where A and B represents the dimensions of the edge of a square or rectangular LED array. To achieve a uniform appearance for the light engine and duct, the cross section of the duct may be designed to correspond to the same shape and size of the output end of the light collimator. Accordingly, it has roughly the dimensions of 3A×3B, and may be a square or a rectangle. Notwithstanding the above, a duct with circular or elliptical cross section may also be used if the light collimator has the shape of a conical frustum.
Example 1Taking an LED array that is 25 mm×25 mm in size as an example, the above design rule requires the area of the input end of the light collimator to be about 25 mm×25 mm in size. Correspondingly, the output end of the light collimator is designed to be 75 mm×75 mm in size. The length of the light collimator may be designed to be 300 mm. Since each duct is about 1.2 meters in length, in order for the light engine housing 120 to have the same length, the heat sink and driver circuit portion of the light engine may set to about 900 mm in length.
Example 2Taking an LED array that is 25 mm×25 mm in size as an example, the above design rule requires the area of the input end of the light collimator to be about 25 mm×25 mm in size. Correspondingly, the output end of the light collimator is designed to be 75 mm×75 mm in size. The length of the light collimator may be designed to be 360 mm. Since each duct is about 1.2 meters in length, in order for the light engine housing 120 to have the same length, the heat sink and driver circuit portion of the light engine may set to about 840 mm in length.
Example 3Taking an LED array that is 15 mm×15 mm in size as an example, the above design rule requires the area of the input end of the light collimator to be about 15 mm×15 mm in size. Correspondingly, the output end of the light collimator is designed to be 45 mm×45 mm in size. The length of the light collimator may be designed to be about 180 mm. Since each duct is about 1.2 meters in length, in order for the light engine housing 120 to have the same length, the heat sink and driver circuit portion of the light engine may set to about 102 mm in length.
The above examples illustrate the use of one design rule which is by no means necessary or optimal for the operation of the lighting system. Other design rules may be applied depending on space limitations, size specifications of the lighting system, and the characteristics of the light source, for example.
Further embodiments of the invention are described in the following paragraphs.
Light Output Surface.To provide a simple light output surface with good light output performance, it may be preferable to use any transparent substrate for the light output surface, optionally combined with a suitable optical film component that is appropriate for the desired performance, such as a diffuser layer, or a polarizer. For example, to achieve good brightness, the light output surface may comprise a brightness enhancement film. A commercially available example is the 3M Vikuiti™ Brightness Enhancement Film (BEF), comprising optical films with prismatic structures microreplicated throughout the film may be used to increase reflection and refraction of light rays. Another type of optical film that may be used to enhance light output is a reflective polarizer brightness enhancement film. A commercial example is the 3M Vikuiti™ Dual Brightness Enhancement Film (DBEF). Optionally, different layer arrangements of BEF and DBEF may be used: one may deploy an individual layer of BEF for the light output surface, or an individual layer of DBEF, or a plurality of BEF layers, or a plurality of DBEF layers, or a combination of BEF and DBEF layers. Additionally, light diffuser films may be used in conjunction with BEF and DBEF films to diffuse incident light from a light source. Commercially available examples include 3M Envision™ Diffuser Films 3735-50 or 3735-60. In daylight applications, 3M Day Light films DF2000 comprising a polymeric film that provides high luminous reflectivity may be used. As described in foregoing paragraphs, light turning films such as 3M Transmissive Right Angle Film II (TRAF) may be used. These films may be used singly, or in combination. For structural support, each optical film layer or multi-layer film stack may be affixed on transparent glass or polycarbonate or other equivalent transparent substrate. 3M Optically Clear Adhesives (OCA) may optionally be used to provide adhesion between the optical layers and/or substrates; mechanical fastening of individual optical layers may be done as an alternative to optically clear adhesives; as a further alternative, the margins of the optical film layer contacting the substrate may simply be provided with double sided adhesive tape without interfering with light transmission through the optical layer. An alternative that dispenses with the use of a transparent substrate is to have the optical film layer stiffened by providing a layer of polyethylene terephthalate (PET), or biaxially oriented polypropylene film (BOPP), or cast polypropylene on the optical film.
Alternative to the use of optical films for the light output surface is the use of reflectors, e.g. conventional mirrors. In one embodiment, the duct comprises a plurality of light output surfaces, each light output surface comprising a mirror capable of being actuated to a position in which light transmitted through the duct is incident on the mirror and reflected out of the duct. A mirror may be mounted at each light output surface and may be mechanically actuated to reflect light out of the duct. The mirrors may be tilted at any desired angle to reflect light out of the light duct. Referring to
The duct may comprise a plurality of light output surfaces. In some embodiments, the light output surface is located on either one or a combination of the bottom surface, top surface or lateral surface of the duct relative to the duct's mounted position. Light output surfaces may be located not only at the bottom surface (opposite the surface facing the wall) of the duct, but may also be located on lateral sides of the duct. In some embodiments, sections of the duct may comprise a transparent material e.g. polycarbonate, or a white or colored translucent material, e.g. a white acrylic duct, or cast acrylic plexiglass duct, as may be dictated by aesthetic and practical considerations of the application. More generally, mirror-lined ducts may be used in the lighting system.
Modular Construction.In some embodiments, the light engine, duct and the collimator are made separately as modules, to be assembled during installation. As shown in
Although the present invention has been described with particular reference to preferred embodiments illustrated herein, it will be understood by those skilled in the art that variations and modifications thereof can be effected and will fall within the scope of this invention as defined by the claims thereto now set forth herein below.
Claims
1. A lighting system comprising: wherein
- a duct providing a light transport passage for transporting light along a propagation direction through the duct, the duct comprising a longitudinal axis and one or more light output surfaces through which light may be emitted,
- a light collimator having an input end and an output end,
- a light source arranged to direct light into the input end of the light collimator,
- a heat sink thermally coupled to the light source, and
- driver circuit for powering the light source,
- at least one of the light collimator, light source, heat sink and driver circuit is arranged away from the longitudinal axis of the duct.
2-3. (canceled)
4. The lighting system of claim 1, wherein the light collimator, light source, heat sink and driver circuit are arranged away from the longitudinal axis of the duct.
5. The lighting system of claim 4, wherein the light collimator, light source, heat sink and driver circuit are arranged in a single file and at an angle of 90° to the longitudinal axis of the duct.
6. The lighting system of claim 4, wherein the light collimator, light source, heat sink and driver circuit are arranged in a single file and positioned parallel to the longitudinal axis of the duct.
7. The lighting system of claim 4, further comprising a joint connecting the light collimator to the duct.
8. The lighting system of claim 1, wherein the light source comprises an array of LEDs, said array of LEDs arranged on a first surface of the heat sink, and the driver circuit arranged on a second surface of the heat sink.
9. (canceled)
10. The lighting system of claim 1, wherein the light engine housing is thermally coupled to the heat sink and configured as a secondary heat sink.
11. (canceled)
12. The lighting system of claim 1, wherein the light collimator comprises a pyramidal or conical frustum.
13-14. (canceled)
15. The lighting system of claim 7, wherein the joint or bend is configured into a L-shape, T-shape or E-shape.
16. The lighting system of claim 1, further comprising a second light source arranged at an opposing end of the duct.
17. The lighting system of claim 1, wherein the duct comprises a plurality of light output surfaces, each light output surface comprising a multilayer optical stack comprising
- a reflective layer arranged to face the duct, said reflective layer having one or more perforations for transmitting light,
- a polished metal substrate layer having one or more perforations aligned to the perforations of the reflective layer,
- and
- one or more optical films arranged over the perforations for processing light leaving the duct.
18. The lighting system of claim 1, wherein the duct comprises a plurality of light output surfaces, each light output surface comprising one or more optical films.
19. The lighting system of claim 18, wherein the optical films are selected from one or a combination of a light turning film, a polarizing film, a reflective polarizing film, a brightness enhancement film, a day light film, and a light diffuser film.
20. The lighting system of claim 1, wherein the duct comprises a plurality of light output surfaces, each light output surface comprising a mirror capable of being actuated to a position at which light transmitted through the duct is incident on the mirror and reflected out of the duct.
21-23. (canceled)
24. The lighting system of claim 1, wherein a plurality of ducts are connected together, each duct comprising a sleeve section at one end and a flared section at the other end, the sleeve section of each duct capable of mating connection with the flared section of another duct.
25. A light collimation module comprising a light collimator coupled to a duct, the light collimation module usable in a lighting system comprising: wherein
- a duct providing a light transport passage for transporting light along a propagation direction through the duct, the duct comprising a longitudinal axis and one or more light output surfaces through which light may be emitted,
- a light collimator having an input end and an output end,
- a light source arranged to direct light into the input end of the light collimator,
- a heat sink thermally coupled to the light source, and
- driver circuit for powering the light source,
- at least one of the light collimator, light source, heat sink and driver circuit is arranged away from the longitudinal axis of the duct.
26. The lighting system of claim 24, wherein the light collimator comprises a plurality of individual light collimators arranged together.
27. The light collimation module of claim 26, wherein the duct comprises a plurality of light output surfaces, each light output surface comprising one or more optical films selected from light turning films, polarizing films, reflective polarizing films, brightness enhancement films, and diffuser films.
28. The light collimation module of claim 26, wherein the duct comprises a mirror-lined duct.
29. The light collimation module of claim 28, wherein the internal surface of the mirror-lined duct has a light reflectance of at least 70%.
Type: Application
Filed: Aug 24, 2015
Publication Date: Jul 27, 2017
Inventor: Andrew T. Tio (Singapore)
Application Number: 15/328,264